Soluble photographic layers of colloidal gums and process for conditioning such gumsfor such use



Feb. 27, 1945. I F. w. H. MUELLER 2,370,321

SOLUBLE PHOTOGRAPHIC LAYERS OF COLLOIDAL GUMS AND PROCESS FOR CONDITIONING SUCH GUMS FOR SUCH USE Filed April 25, 1942 g sure-e H44 ms 9' Z Era/4am LAYEE A pseflan/swrsuppaer 6/41/52 HAL/0E EMULSION ans-2 INVENTOR fik/rz G1 64 Mar-245E TTO NEYS Patented Feb. 27, 1945 UNITED STATES PATENT OFFICE SOLUBLE PHOTOGBAPHIC LAYERS OF COLLOIDAL GUMS AND PROCESS FOR CONDITIONING SUCH GUMS FOR SUCH- Fritz w. n. Mueller, Binghamton, N. Y. Application April 25, 1942, Serial No. 440,430

Claims.

The present invention relates to soluble photographic layers prepared from agar-agarand to the use of such layers as an adhesive in stripfilm. This application constitutes a continuationin-part of my prior application Serial No. 357,609, filed September 20, 1940, now U. S. P. 2,330,905.

Colloids are extensively used in photography in the manufacture of layers such as surface-, back-, and anti-halation layers and adhesive layers. In the latter case they are extensively employed in the formation of the so-called photographicstrip film. Such film, as known, essentially comprises, in'the order of their arrangement, a temporary support, a strip or adhesive layer, a permanent support and a photographic emulsion. The prior art has proposed to utilize for this purpose such colloids as soluble gelatine, glues, dextrines' and the like. Inasmuch as such colloids are naturally of an adheslve character, they may also be employed for the formation of the other layers previously mentioned, the character or property in question permitting them when cast into layers to be united directly to the film base or other layers thereon.

Such substances have certain disadvantages when used in these relationships. In U. 8. P. 2,275,617 it was proposed to overcome these disadvantages, particularly in the manufacture of adhesives for strip film, by employing in lieu of said colloids certain vegetable mucilages and pecto celluloses. It was round that these substances exhibited the peculiar property of having the viscosity thereof greatly diminished by photographic fixing baths, particularly those containing sodium thiosulphate, so that when strip film containing the same was immersed in such baths, the bond between the temporary support and the pent support was destroyed. It was further noted in said patent that this property is not common to all colloids, and in this connection reference was made inter alia to agaragsr. This substance, though good dition it for use as a strip film adhesive by increasing its solubility without impairing its VIP carbohydrate component intact.

acid, acetic acid, formic acid, propionic acid and the like. The acids serve to catalyse hydrolytic reactions independently of the nature of the colloid hydrolysed or ofthe'bonds to be hydrolysed. Thus, they operate equally on carbohydrates, proteins or fats, the degree of hydrolysis being dependent to a certain extent at least upon the duration of their action.

The same; however, does not apply to the action of enzymes. the material treated, different enzymes being required for carbohydrates, proteins and the like. Thus, for instance, the application of a carbohydrate splitting enzyme will leave the protein component entirely intact, whereas the application of a protein splitting enzyme will leave the Agar-agar as is known from the literature contains about 17% of proteins and about 40% of water-soluble carbohydrates, known as gelose (GRAFE, Hdb. org. Wk (1931), vol. 112,

page 730) Due to the high protein content and carbohydrate content of agar-agar, it is not possible to hydrolyse or degrade the same to the extent that the resulting product will be soluble in the usual aqueous fixing baths by utilizing a carbohydrate splitting enzyme alone or a protein splitting enzyme (proteolytic enzyme) alone. On the contrary, in order to obtain the desired degree of hydrolysis, it is necessary to use both a proteolytic enzyme and a carbohydrate splitting enzyme in sequence, it being immaterial, however, which of the two enzymes is first employed. In this respect, agar-agar-differs from most colloids, such as carsgeen, extract of lichen and the like, which are capable of beingsolubilizedto the desired de ree by the utilization of a single type of enzyme. Suitable enzymes of the proteolytic type is the product sold by Roehm 8: Haas Co.,

' so Philadelphia, Pa., under the trade mark Orthozyme X (activated trypsin), pepsin and the like. Suitable enzymes of the carbohydrate splitting type are the products sold by Roehm it Haas 00., Philadelphil. Pm. under the trade mark "Pectinol 100," and containing pectinssc as the Their action is specific as regards bohydrate splitting enzymes, the application being in sequence, as previously stated.

The degree-of solubility of the degraded agaragar will depend to some extent on the agent employed but it is .to be emphasized again that the hydrolysis must be carried to such an extent that a product readily soluble in the usual aqueous fixing, baths will ensue. However, the, time of treatment must not be extended so far as to result in products sticky in character. Because the extent of treatment will vary, a specific statement of time cannot be given. This, however, is immaterial since a simple test will enable the operator to determine when he is within the limits just given.

The invention is further exemplified by the accompanying self-explanatory drawing and the following examples, but it is to be understood that the examples are merely illustrative of the invention. The drawing illustrates in section in Fig. I strip film containing a colloid treated according to the invention, as the adhesive layer and in Fig. H film carrying a layer of a colloid treated according to the invention as an antihalation backing.

Example 1 A solution of 2.5% of agar-agar in 2% acetic acid is heated to boiling for 15 to minutes, and thereafter quickly cooled. The filtered solution is cast to form the adhesive layer B in the film of Fig. I. The adhesive film dries with a smooth and even surface without showing any signs of stickiness.

Example 2 I A solution of agar-agar treated as in Example 1 is cast to provide the anti-halation backing R of-Fig. II. This film, as well as that of Fig. I, is soluble in water and mixes readily with antihalation dyes. To facilitate coating there may be incorporated in the solution a suli'onated carboxylic acid amide of the type disclosed in U. 8. Patent 1,932,179.

Example 3 A 5% solution of agar-agar, disinfected with phenol, is buffered to pH 4.5 with Mcllvaine buffer (Handbook of Chemistry and Physics, 16th edition, page 577). 250 mg. per liter of the product sold by the Roehm 8r Haas Co. of Philadelphia, Pa., under the trade-mark Pectincl 100" are added and the solution kept in an incubator for 48 hours at 45 C. The pH is then increased to 7.5 whereupon 250 mg. per liter oi the product sold by Roehm 8r Haas under the trade-mark Qrthozyme X are added and again the solution held in the incubator for 72 hours. After removal from the incubator, the solution is heated to to C. to stop the action of the enzymes. The solution is filtered while hot from undissolved particles and may then be used in strip film, surfaceand anti-halation coatings and the like.

I claim:

1. A photographic strip film comprising a permanent support having a silver halide emulsion thereon and a temporary support and containing as the adhesive layer between the temporary and permanent supports the hydrolyzed colloid prepared by subjecting an agar-agar high in nitrogen to hydrolysis by means of a hydrolyzing agent selected from the class consisting of free acids and a combination of enzymes employed in sequence, while heating until the colloid becomes readily soluble in the usual aqueous fixing baths and when cast forms a transparent non-sticky layer.

2. The photographic strip film of claim 1, wherein the hydrolyzed colloid is prepared by the action in sequence of a carbohydrate splitting enzyme and a proteolytic enzyme. v

3. The article defined in claim 1 wherein the agar-agar subjected to hydrolysis contains on the order of 17 per cent of proteins and about 40 per cent of water-soluble carbohydrates.

. 4. A photographic strip film comprising a permanent support having a silver halide emulsion thereon and a temporary support and containing as the adhesive layer between the temporary and permanent supports the hydrolysed colloid prepared by subjecting agar-agar to hydrolysis by means of a free acid while heating until the colloid becomes readily soluble in the usual aqueous fixing baths and when cast forms a transparent, non-sticky layer.

5. A photographic strip film comprising a permanent support having a silver halide emulslon thereon and a temporary support and containing as the adhesive layer between the temporary and permanent supports the hydrolyzed colloid prepared by heating agar-agar with acetic acid until the agar-agar becomes readily soluble in the usual aqueous fixing baths and when cast forms a transparent, non-sticky layer.

FRITZ W. H. MUELLER. 

